MRI of the 'Tiger': a case series.

BACKGROUND

Sawtooth cardiomyopathy (CMP) or 'Tiger heart' is a rare form of CMP of which only several cases have been described in literature. Hereby, we present two cases with this phenotype using cardiovascular magnetic resonance (CMR).

CASE SUMMARY: The first case was asymptomatic and referred for family screening. Cardiovascular magnetic resonance showed non-dilated, non-hypertrophic left and right ventricles with good systolic function. Morphologic abnormalities were seen with multiple band-shaped muscular bridges from the septal to the inferior wall fitting 'sawtooth CMP'. The second case had a recent stroke at young age and was referred for analysis regarding a possible source of cardiac embolism. Cardiovascular magnetic resonance showed a dilated left ventricle with a basal inferoseptal aneurysm and severely impaired systolic function. Late enhancement images showed transmural fibrosis apical inferior.

DISCUSSION: These two cases of 'sawtooth CMP' illustrate a varying clinical picture from asymptomatic with normal ventricular function to dilated CMP with severely impaired systolic function. Reviewing current literature, we found several other case reports on sawtooth CMP. Sawtooth CMP was associated with various clinical sequelae including ventricular dysfunction, arrhythmias, and stroke. Non-invasive cardiovascular imaging was essential in their diagnostic work-up. The morphologic findings have been suggested to be different from established criteria to diagnose hypertrophic CMP or left ventricular non-compaction. The long-term prognostic implications are currently unknown.